Alan Stern wrote:
On Mon, 19 Jan 2009, Sam Liddicott wrote:
My USB hard disk has a built-in hub as lsusb shows:
Bus 005 Device 006: ID 1058:0702 Western Digital Technologies, Inc.
Passport External HDD
Bus 005 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
This doesn't show anything one way or another, since it doesn't
indicate whether device 006 is a hub or not.
Device 001 is a hub, though, surely? It vanishes when I remove the USB
hard disk.
Device 001 is always a root hub, a virtual hub associated with a USB
host controller. It's not a real hub. It shouldn't vanish unless you
unload the host controller driver.
You are right, I don't know why I thought it vanished when I removed the
disk.
So my removable disk does NOT have a built-in hub
Could this be a power issue? If the cheap hub is bus-powered, your
musicpal device might not provide enough Vbus power for the hub to
work. Or for the hub + USB stick.
or for the hard disk.
I think this is now the most plausible explanation, now it's clear that
it was not properly working with the hub.
..
If the kernel has kexec, I might manage what you say, otherwise it's
going to be fun and games as there's only about 200K spare in the flash
anyway...
Doesn't your boot loader support loading a kernel image from a network
connection?
I'll check; but I don't think so.
However I'll try some powered USB hubs, and if they work then it must be
as you suggest, a power issue.
Thanks very much for the benefit of your knowledge. I'll report back
what I find.
Sam
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